In the paper converting industry, large rolls of web material known as parent rolls are rolled up on a reel after a web manufacturing process, such as in the production of tissue and other paper products. The parent rolls are usually transported to an unwind station for unwinding and further processing.
Conventional unwind stations or systems known as xe2x80x9cunwindsxe2x80x9d are used particularly in bath and towel winder machines for the production of bathroom tissue and kitchen toweling and in interfolder and multifolder machines for individual folded sheet products such as facial tissues, hand sheets, and wipers. The products can be produced in wet or dry forms to fit specific customer needs. In these various machines, the unwinds unwind the parent rolls for calendering, embossing, printing, ply-bonding, perforating and other conversion and finishing operations. Once the web material or sheets of the unwound parent rolls have been subjected to the various conversion and finishing operations, the sheets are re-wound into retail-sized logs, cut, and packaged as consumer-sized rolls.
The typical unwind uses core shafts or plugs to support the unwinding parent roll on an unwind stand. Usually, belts driving on a surface of the parent roll provide unwinding power, whereas center driving has been used mainly in film unwinding. When the parent roll runs out in the typical unwinding operation, the spent parent roll, core, and core shaft must be removed from the machine and each new parent roll positioned on the unwind stand with an overhead crane, cart, tractor, extended level rails, or similar roll positioning device.
Traditional unwinds generally suffer from parent roll change down time, thread-up delays, splicing waste, and/or waste from layers of web left on the core. In bath and towel winders and multifolder and interfolders, for instance, parent roll change down time significantly reduces total available machine run time and requires an expenditure of manpower to change the parent rolls.
For machines that simultaneously unwind multiple parent rolls, the waste and delay problem is even more serious. In the typical multifolder unwind, a lack of a real-time xe2x80x9cflying-splicexe2x80x9d and inability to individually, automatically change parent rolls within the machine at different times result in delays and unacceptable roll waste. Delays occur when the entire machine is stopped to change out all parent rolls simultaneously and when splicing multiple webs of material together from multiple parent rolls at less than full machine operating speed. Roll waste occurs when some rolls in the machine are not completely unwound but must be changed out when all rolls are changed out during machine stoppage.
Another existing drawback in the industry is that winder, interfolder, and multifolder machines are often limited to their existing xe2x80x9cfootprintxe2x80x9d (e.g., width) due to space and cost limitations. Interfolders and multifolders, for instance, frequently include multiple unwinds installed side by. Current technology for quick roll changing and web splicing includes secondary shuttle unwind stands or turret-type unwind stands that require significantly more complex equipment-and use of floor space. Adding these conventional unwinds requires increasing the footprint of the interfolder. Therefore, such additions are usually impractical and cost prohibitive.
Similarly, due to the large number of unwinds in many multifolders, operator accessibility, floor space utilization, and improvement costs pose problems. Conventional unwinds cannot be added adjacent to existing multifolder unwinds to accommodate formation of 2-ply products without a high capital cost to increase floor space. Hence, machine flexibility is limited and maximum output that can be obtained from a downstream rewinder line is reduced.
Accordingly, there is a need to reduce the time machines are stopped or delayed, to improve efficiency, and to reduce web waste at a reasonable cost.
In general, the present invention provides an unwind system for unwinding relatively large parent rolls of tissue, paper, and similar materials utilizing flying-splice roll changes. The unwind system (xe2x80x9cunwindxe2x80x9d) supports unwinding large rolls of web material while reducing roll change delays and waste. The present unwind also provides operator accessibility needed for multiple unwinds installed on multifolders. Moreover, the unwind permits future growth in roll diameter since the present invention supports driving the parent roll from the center or the surface of the parent roll or both. The component parts of the unwind system with flying-splice roll changing are simple, reliable, and economical to manufacture and use.
In one aspect of the invention, an unwind system includes a kitchen rail, a primary center-drive system, and an elevator assembly. A parent roll is captured, aligned, and held in a run position on the kitchen rail by the elevator assembly and a pivoting center-drive arm of the primary center-drive unwind system. In this aspect, a coreshaft of the parent roll is center-driven using a double-sided timing belt mounted on the pivoting arm. The center-drive pivoting arm minimizes space requirements by limiting a width of the unwind system to substantially a combined 10 width of the parent roll and the kitchen rail. Also in this aspect, a web sheet path of the parent roll facilitates an operator""s access for manual thread-up of the web sheet when necessary.
In another aspect of the invention, a method for unwinding a parent roll is provided. The method includes the steps of providing at least one parent roll staged on a kitchen rail at a park position. Another parent roll is positioned in a run position on the kitchen rail between an elevator and a drive arm. As the parent roll in the run position unwinds, a surface belt of a secondary unwind drive contacts the parent roll while the pivoting arm of the primary unwind drive disengages and pivots away from the parent roll. The elevator raises the parent roll to a secondary unwind position while the parent roll in the park position is released and moved to the run position. An operator prepares the new parent roll in the run position for splicing by applying two-sided tape or other adhesive and a splice marker. Further steps of this aspect of the invention include pressing the webs of the removed parent roll and the new parent roll together. The older parent roll web is cut and the splice marker is tracked to automatically remove the splice downstream.
In another aspect of the invention, the elevator and secondary unwind arm assembly can be installed with other types of primary unwind designs to reduce roll change delay time and roll waste.
Other aspects and advantages of the invention will be apparent from the following description and the attached drawings, or can be learned through practice of the invention.